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On June 26, Fallujah—the first Iraqi city to fall to the so called Islamic State—was finally declared fully liberated by Iraqi Prime Minister Haider al-Abadi. It was a significant victory for the much-maligned Iraqi armed forces. They had been fighting to clear the city of about a thousand ISIS militants for five weeks. Just 30 miles west of Baghdad, Fallujah has been a springboard for car bomb attacks in the Iraqi capital since it was seized by the so-called Islamic State in January 2014.

Between the uproar over Brexit and the bizarre gyrations of the current presidential election campaign, the Iraqi victory seems to have barely caught the attention of the American public. Yet for 12,000 Americans, both active duty and former Marines and soldiers, this was a fight that mattered more than they could say.

They have been there before.

In the fall of 2004, two U.S. Marine reinforced regimental combat teams—the rough equivalent of a division—wrested Fallujah from 4,000 diehard jihadist insurgents in what proved to be the costliest, most intense battle of the entire Iraq War (2003-2011).

The chief objective of the American campaign plan during the fall of 2004 was to eliminate the major safe havens of a burgeoning insurgency in advance of Iraq’s first parliamentary elections after the American invasion. The legitimacy of the interim government, and the upcoming elections, appeared to hang in the balance. Fallujah, a city of 250,000 less than an hour’s drive from Baghdad, was the mother of all safe havens.

This metropolis on the edge of the desert had a well-earned reputation as a home for former Baathist party enforcers and other criminal elements. It was a squalid, unattractive place, unfriendly to strangers—a city, writes military historian Bing West, “comprised of two thousand blocks of courtyard walls, tenements, two-story concrete houses, and squalid alleyways. Half-completed houses, garbage heaps, and wrecks of old cars cluttered every neighborhood.”

Gen. John Sattler, top commander of the Marines in Iraq, remarked in September 2004 that no Marine vehicle could move in or around Fallujah without being fired on. The Corps couldn’t wait to assault the city and mix it up with a colorful mélange of al Qaeda, freelance Islamist extremists from across the Middle East, and several Sunni militia groups.

The previous April the Marines had begun to put the hurt on the Fallujah insurgency, only to be pulled out of the city in the middle of a tough fight by an Iraqi government that feared the repercussions of heavy civilian casualties. The Marine command was not pleased.

Unlike the recent struggle to take the city back from ISIS, the outcome of the fall 2004 encounter was never really in doubt. Superior numbers, training, and an immense advantage in firepower insured that the city would fall to the Americans. The critical questions were, how much blood and treasure would it take to wrest the city from the enemy? Would the city have to be destroyed to be saved? And most importantly, would victory in Fallujah reverse the momentum of an insurgency steadily growing in both numbers and intensity across much of the country?

Sattler’s Marines had the luxury of several months to prepare their plan of attack, and it proved to be a very good plan indeed. A preliminary feint from the southwest 24 hours before the main assault would draw off considerable numbers of jihadists from the northern sector of the city, the direction from which the main attack would proceed. A U.S. Army armored brigade had thrown a tight cordon around the entire city, preventing reinforcements or resupplies from reaching the enemy.

Crucially, the Iraqi government and the Americans had managed to persuade/cajole well over 90 percent of the city’s populace to evacuate their homes, so if the American infantry ran into exceedingly tough resistance, as indeed they did, they could employ the full range of their lethal supporting arms—Abrams tanks, the steel rain of 105-mm shells from circling C-130 gunships, jet fighter-bombers, and of course, artillery fire—without fear of causing large numbers of civilian casualties.

During the cold, rainy evening of November 8, the northern rim of the city came under a thunderous and sustained bombardment from artillery and warplanes. Hundreds of 155-mm shells and 500-pound high-explosive bombs shook the earth across a three-mile front, obliterating a train station and a large apartment complex on the outskirts of the city.

An eerie silence followed. Suddenly two Regimental Combat Teams of Marine infantry and Army armored battalions, about 8,000 men in all, crossed a railroad embankment, and began to push south into the city proper. Within seconds, the American advance was met with an avalanche of small arms and mortar fire. Over the earsplitting din of simultaneous fire from thousands of weapons, loudspeakers on Marine Humvees blared Wagner’s “Ride of the Valkyries,” and insurgent commanders barked orders in Arabic over their own loudspeakers, ensconced in the minarets of several of the city’s 200 mosques.

So began ten straight days of brutal, close-in fighting to sweep through this labyrinth of a city, north to south, and wrest it from the insurgents’ grasp. The jihadists had spent the better part of half a year constructing bunkers, strong points, and laying out avenues of retreat, and ambush sites. Hundreds of rooms and entire houses had been expertly booby trapped, and IEDs had been liberally planted in the streets and alleys. Road blocks of Jersey barriers and junk cars designed to funnel the attackers down lethal avenues of approach seemed to be around every other corner.

As the insurgents came under fire from the advancing American battalions, they tended to react in one of two ways: they either held their ground and fought to the death, or they rapidly retreated down side streets or into alleys, hoping to lure the Marines and soldiers into prepared kill zones

Dexter Filkins, a New York Times war correspondent who had covered half a dozen wars and was imbedded with a Marine rifle company in Fallujah, described the combat there as “a qualitatively different experience, a leap into a different kind of battle.” He was hardly the only veteran reporter to register that reaction. Filkins himself narrowly escaped death at least once in the fighting, and saw several of the men with whom he was embedded die as well.

The battle “was intense, close, and personal, the likes of which have been experienced [by U.S. forces] on just a few occasions since the battle of Hue City in the Vietnam War . . . There were no real front lines, because [the insurgents] would get behind you constantly,” recalled General Sattler after the battle.

How right the general was! On November 9, after 16 straight hours of fighting to take a fortified mosque being used as command post, men in B Company, 8th Marines, saw a car pull up behind them. Out poured six insurgents wielding rocket propelled grenades and AK-47s. The Marines opened up, killing four in a matter of seconds, before they were able to get off a single round of fire. The two remaining insurgents dashed for a courtyard, where they were rapidly cornered by several Marines. Suddenly, one of the insurgents pulled a cord on his suicide vest, sending himself and his brother fighter to instant martyrdom.

Virtually every infantry company in Fallujah could report at least one such encounter by battle’s end.

Forty-eight hours into the fight, the Marines had advanced methodically through about one third of the city, and seized the government center, having leveled several hundred enemy strongpoints to rubble with air strikes, tank fire, and armored bulldozers that proved critical in keeping the advance moving. (So entrenched were the insurgents that by the end of the fight, the Marines had been forced to level some 10,000 of 50,000 residences—most were rebuilt at American expense.)

On the fourth day of the battle, November 12, both Regimental Combat Teams crossed Highway 10, the six-lane, east-west artery that divided the northern half of the city from the grimy industrial southern half. Southern Falluja had been far more heavily fortified than the north. Here the Marines came up against dozens of unyielding defensive pockets, and had to fend off a series of suicidal counterattacks that left the streets littered with bloated, stinking corpses. “Almost as soon as the insurgents were dead, the dogs started gnawing on their bones,” recalled a Marine officer. Heavy rains prevented the authorities from burying these bodies for several days.

It sometimes became necessary to slip small units of Marines in behind the enemy-held pockets in order to clear them out. Marine Capt. Elliot Ackerman’s platoon slipped behind insurgent lines in the middle of the night, and took up residence in a four-story building. Author Bing West, who was imbedded with a company of Marines in the battle, gives this vivid account of what followed in No True Glory:

At first light . . . on both sides of their building, insurgents were slipping forward in bands of four and six . . . They were unaware of the Marines until the M16s opened up, hitting three or four before the others ducked into the surrounding buildings.

The insurgents scattered for cover, then converged on the platoon. Within minutes the fighting fell into a pattern. The platoon held a stout building with open ground on all sides, which made a frontal assault suicidal. Instead, enemy snipers, RPG teams, and machine-gunners were running from floor to floor and across the roofs of the adjoining buildings looking for angles to shoot down.

The Marines tried to pick out a window or a corner of a building where an insurgent was hiding and smother it with fire. The shooters on both sides were like experienced boxers, jabbing and weaving and never leaving themselves open. The Marines punched mouse holes in the walls and threw up barricades in front of their machine guns, shifting from room to room every ten minutes.

A particularly effective method for reducing stubborn enemy positions within apartment buildings or other large structures was for the American artillery to fire a “shake and bake” mission: First, a battery of cannons fired incendiary white phosphorus smoke rounds into a building to flush the insurgents outside, and then, after a short delay, they bracketed the building with high explosive rounds to kill them as they exited.

After ten days of grinding, close combat, the Americans, supported by two elite Iraqi Army battalions, had captured the city.

Then came the massive mopping up effort. The fighting was not as intense as it had been during the clearing phase, but it was still dangerous, exhausting work. More than 20,000 structures were searched and cleared—some as many as three times, as insurgent hangers-on re-infiltrated previously cleared dwellings. If the Marines were forced to withdraw from a house due to heavy fire from inside, they would reduce it to rubble by attaching a patch of C-4 explosive to two propane canisters and throwing them through a window.

By the time it was all over on December 23, U.S. forces had uncovered more than 450 weapons caches, three torture chambers, one of which contained a live prisoner who’d had his leg sawed off, and 24 bomb-making factories. According to a log cited in Bing West’s book, one Marine platoon cleared 70 or more buildings a day for more than a week, during which time they engaged in an average of three firefights a day, and killed 60 insurgents.

The final butcher’s bill for taking Fallujah was 95 Americans killed in action, and 450 seriously wounded. According to a report from Gen. George Casey, commander of all coalition forces in Iraq, of the 8,400 insurgents killed in 2004, 2,175 had fallen in the Battle of Fallujah. Unfortunately, hundreds of Islamist insurgents had either left Fallujah before the battle or slipped through the cordon in small groups and went on to join their brothers to spark new uprisings in Mosul, Ramadi, and East Baghdad.

Meanwhile, Abu Musab al-Zarqawi, leader of al Qaeda in Iraq, had slipped through the cordon around Fallujah on November 8 and made his escape, but his second in command, Omar Hadid, had been killed in the fighting.

The Battle of Fallujah waged in late 2004 joins the ranks of Tarawa, the Chosin Reservoir, and the Battle for Hue as one of the Marine Corps’ bitter, hard-won triumphs that unfortunately had little strategic impact on the war of which it was a part. One veteran of the battle, Col. John Toolan, was hardly the only thoughtful officer to question whether the kind of fighting that had gone on in Fallujah was counterproductive in the long run. “What’s the impact on a ten-year-old kid when he goes back and sees his neighborhood destroyed? And what is he going to do when he is 18 years old?”

Hearts and minds are not won by leveling cities, and by late 2004, the American military was finally waking up to the fact that it was in the middle of a protracted insurgency war, and hearts and minds were what it was all about.

Immediately after Fallujah, a senior military intelligence officer with a Ph.D. in Islamic Studies painted a grim and startlingly prescient picture of the war in Iraq in a secret briefing for President Bush. The insurgency remained “robust, well-led, and diverse.” It could very well blossom into a full-fledged civil war. The insurgents “have the means to fight this [conflict] for a long time, and they have a different sense of time than we do, and are willing to fight.”

Twelve years later, the Marines have left Iraq, the insurgents remain, and the country finds itself deeply mired in civil war. But Fallujah has at last been retaken, and the Islamic State is clearly on the defensive—at least in Iraq. And that’s good news for Iraq, for the United States, and for the American Marines and soldiers who fought the good fight for Fallujah in 2004.